Rechargeable batteries are wildly used in electronic products, such as laptops, mobile phones, MP3 players, personal digital assistants (PDAs), etc. In practice, for different design purposes of products, rechargeable batteries can be either detachable or non-detachable types. Many of these products have the rechargeable batteries be charged when the power is running out. However, under this situation, other designers would consider life time of a non-detachable battery and let it be protected from being charged.
U.S. Pat. No. 7,068,484 reveals a device for rechargeable battery protection (shown in FIG. 1). The device detects a voltage and a current of a power supply circuit and has a protection circuit in a microcomputer. Software is used to determine whether the power supply circuit is on or off so that the rechargeable battery is protected. Although the circuit is miniaturized to a microcomputer, it still needs the help of software. Besides, '484 is not able to switch on/off the power supply circuit when the rechargeable battery has no power but a charger is ready to charge.
This invention provides a suitable solution to the problems mentioned above.